Air operated tool

ABSTRACT

An air operated tool wherein a motor assembly is employed which includes a plurality of tandemly arranged out of phase motor units, each motor unit including a cylinder which has a continuously open intake port and a continuously open exhaust port, a shroud is movably mounted within the cylinder and is continuously biased into engagement with a rotor which is rotatably mounted within the cylinder, the rotor being eccentrically mounted on a shaft. The motor assembly is mounted within a housing, the outer surface of which includes a series of convolutions, one of the convolutions to cooperate with a securing element of a handle, the securing element of the handle being forcibly moved by means into engagement with a convolution.

Unite States atet 1'19] Hedriclt Dec. 3, 1974 AIR OPERATED TOOL Primary ExaminerFrank L. Abbott [75] inventor: John R. l-ledrlck, La Crescenta, Attorney Agent or firm-Robert Geauque Calif. [57] ABSTRACT [73 Asslgnee: Pevr'ck Engmeermg Sun An air operated tool wherein a motor assembly is em- Vaney Cahf' ployed which includes a plurality of tandemly ar- [22] Filed; Ju 3, 1973 ranged out of phase motor units, each motor unit ineluding a cylinder which has a continuously open in- [21] Appl' 368313 take port and a continuously open exhaust port, a shroud is movably mounted within the cylinder and is [52] US. Cl 173/170, 173/163, 251/40 continuously as into gag m nt ith a r tor [51] Int. Cl B23b 45/04 which is rotatably mounted within the cylinder, the [58] Field of Search 173/170; 415/503; 251/40; rotor being eeeentrically mounted on a shaft.- The 74/523; 316/47, 50 motor assembly is mounted within a housing, the outer surface of which includes a series of convolutions, one [56] Ref e Cit d of the convolutions to cooperate with a securing ele- UNITED STATES PATENTS ment of a handle, the securing element of the handle 1,808,48l 6/1931 Slater 173 170 g gi fi l g moved by means mm engagement 3,643,750 9/1970 Allen 173/170 6 Claims, 15 Drawing Figures PATENT u- ER 319M SHEET 2 BF 4 PATENTEL BEE 3 74 Fig. 8.

SHEEF 3 0F 4 PATENTELBEB 385L715 SHEH nor 4 BACKGROUND OF THE INVENTION Pneumatic tools are receiving wide acclaim in certain fields. One such field is in medicine wherein such tools are used in surgery. A saw can be used to cut through the bone of a limb to remove a limb, a reamer is used to scrape a bone, or a drill is used to form holes for pins.

The normal way such a tool is employed is that a single tool housing is employed to which the various attachments can be connected. This is undesirable because in some instances it is necessary to interchange tools quickly. Additionally, the person normally employed to interchange the tool is a nurse who is not mechanically minded enough to interchange such tools quickly. Also, the nurses may frequently attach the attachment to the housing improperly as not being tight enough so that the attachment will come loose during usage.

The primary reason for the employment of a single housing and several difierent tool attachments is that the motor mechanism located within the tool housing is quite complex and therefore quite expensive. As a result, hospitals and doctors offices frequently buy only a single tool housing. However, if a tool housing could be made inexpensively enough, it would be desirable to purchase a plurality of such housings, thereby eliminating the interchanging of attachments during the performing of an operation.

SUMMARY OF THE INVENTION The primary objective of the apparatus of this invention is to construct the tool housing with a motor assembly which is simple in construction and much cheaper to manufacture than present housing constructions. One way in which the apparatus of this invention has achieved the simplicity of construction is by elimination of valving with the intake port and the exhaust port of the motor unit. The intake port and exhaust port formed within the cylinder of the motor unit of this invention are continuously open. An eccentric rotor is rotatably mounted within a chamber in the cylinder. A portion of the surface of the rotor is formed arcuately to correspond to the arcuate configuration of the interior wall of the cylinder In this way, as the rotor rotates within the cylinder, an area type of contact is-obtained between the cylinder and the rotor which substantially eliminates leakage from the intake side to the exhaust side. A shroud is mounted within the cylinder between the intake port and the exhaust port and is capable of radialmovement in respectthereto. A pressurized air chamber biasing means is formed within the cylinder to bias the'shroud into continuous contact with the rotor. The rotor is eccentrically mounted upon the shaft with the mass of the rotor being dynamically balanced with respect to the shaft so that undesirable dynamic vibrations are not created during rotational movement of the shaft. This balancing is achieved by removal of a portion of the mass on the enlarged side of the rotor. A thin sleeve surrounds the rotor to cover the space created by the removal of the mass. Normally, there will be at least two motor units employed in tandem in an out-of-phase relationship so that if perchance a single motor unit stops at exactly a dead center position, the

motor can always be restarted because the other motor unit will not be in a dead center position.

. The tool housing which contains the motor assembly includes an outer configuration of a series of convolutions. The convoluted housing facilitates manual grasping by itself with the fingers of the operator to cooperate with the convoluted housing. A pistol grip handle is to cooperate with the housing. The handle includes a pivotal securing means which is to cooperate with one of the convolutions in the housing. The securing means comprises a block which is pivotally secured to the handle and which is contactable by a fastener which is screw threaded in the handle. By inward rotational movement of the fastener, the securing means is pivoted into tight frictional engagement with one of the convolutions of the. housing thereby causing tight securement of the handle to the housing. A trigger is pivotally mounted within the handle and is to cause activation of the valve means located within the housing, thereby supplying air pressure to the motor assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a tool which is to employthe motor assembly of this invention;

FIG. 2 is a top view of the tool of FIG. 1 taken along line 2-2 of FIG. 1; I

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2 showing in more detail the motor construction of this invention;

FIG. 4 is a segmental view of a portion of the structure in FIG. 3 showing the operation of the valve to supply pressurized air to the motor assembly of this invention;

FIG. 5 is a cross-sectional view through a portion of the apparatus of this invention taken along line 55 of FIG. 3;

FIG. 6 is a cross-sectional view through a portion of the apparatus of this invention taken along line 6-6 of FIG. 3;

FIG. 7 is a cross-sectional view through a portion of the apparatus of this invention taken along line 7-7 of FIG. 3;

FIG. 8 is a cross-sectional view through a portion of the apparatus of this invention taken along line 8-8 of FIG. 3;

FIG. 9 is a cross-sectional view through a portion of the apparatus of this invention taken along line 9-9 of FIG. 3;

FIG. 10 is a cross-sectional view through a portion of the apparatus of this invention taken along line 10-10 of FIG. 3;

. FIG. 11 is a cross-sectional view through a portion of the apparatus of this invention taken along line 11-11 of FIG. 3;

FIG. 12 is a partly-in-section view showing the handle disassociated from the motor housing;

FIG. 13 is a cross-sectional view showing cooperation of the handle with the motor housing wherein a first type of fastener means is employed to move the securing block into tight engagement with the motor hous- FIG. 14 is a view similar to FIG. 13 but showing a second embodiment of the fastener means mounted within the handle; and

FIG. 15 is a cross-sectional view taken along line 15-15 of FIG. 13.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENT Referring particularly to the drawings, there is shown in FIG. 1 the tool of this invention which is basically composed of a motor housing 12, a handle grip 14 which has mounted therein a trigger 16, a pressurized air exhaust conduit 18 and an attachment 20 which extends from the motor housing 12. The trigger 16 is to be manually controlled to supply pressurized air to the motor assembly included within the motor housing 12. The attachment 20 is shown in the form of a router. However, it is to be considered within the scope of this invention that the attachment 20 could take the form of a drill, a saw or any other type of tool attachment.

The housing is formed into a series of convolutions 21 adjacent a valve sleeve 22. The function of the convolutions 21 is to facilitate attachment to the handle grip 14. The convolutions 21 also function as a hand grip when it is desired to use the housing 12 without the use of the handle 14. The handle 14 is basically in the shape of a-pistol grip. This has been found to be the most desirable form of grip. The grip 14 includes an interior elongated channel 23. The tubular housing 12 is to be located within the channel 23.

The handle grip 14 assumes a basically bifurcated configuration about the channel 23 forming side walls 25 and 27. Located along the upper edges of each of the side walls 25 and 27 is an inwardly extending flange 29 and 31, respectively. Flanges 29 and 31 are to cooperate with flattened areas 33 and 35, respectively, located upon the tubular housing 12. As a result, the side walls 25 and 27 contain laterally the housing 12 with the flanges 29 and 31 preventing vertical withdrawing movement of the housing 12 from the chamber 23.

In order to place the housing 12 within the chamber 23, it is necessary that the rear end of the tool (which is connected'to attachment 20) be passed through the chamber 23 until the tubular housing 12 fully cooperates within the chamber 23. Full cooperation is noted when the front edge of the handle grip 14 comes into contact with the front convolution 37. It is to be noted that the convolution 37 is slightly larger than the other convolutions. The convolution 37 is to function as a stop to precisely locate the grip 14 with respect to the housing 12. Also, because of the enlarged convolution 37 it is not possible to connect the handle grip 14 with the housing 12 by insertion in the opposite direction, that is, from the front end of the housing 12.

Pivotally mounted by a pivot pin 39 within the handle grip 14 is a securing block 41. The block 41 includes an upper rounded end 43 which is contoured to the curve of the convolutions 21. A set screw 45 is threadably mounted within the handle grip l4 and when tightened is adapted to come into contact with the securing block 41. When the set screw 45 is tightened, the block 41 is caused to be pivotedabout pivot pin 39, thereby forcing the rounded end 43 into tight engagement with the contour of the convolutions 21. This tightening action forces the housing 12 into tight engagement with the flanges 29 and 31. Therefore, by tightening of the 'set'screw 45, positive locking action occurs between the handle grip 14 and the tubular housing 12.

Also pivotally mounted upon. the pivot pin 39 is the trigger 16. The trigger 16 is mounted within a groove 47 formed within the securing block 41. The aft end 49 of the trigger 16 is to contact a valve sleeve 22. By a pulling of the trigger 16, the valve sleeve 22 is depressed due to the pivoting of the trigger 16. It is to be noted that the trigger 16 and the securing element 41, when the handle grip 14 is disassociated from the hous ing 12, can both be' pivoted almost 180 to facilitate cleaning of the handle grip l4 interiorly thereof adjacent the set screw 45.

Referring in particular to FIG. 14 of the drawings, there is a modification wherein no set screw 45 is employed but instead an elongated screw 51. The screw 51 is threadably, mounted from the lower end of the handle grip 14 until the inner end of the screw 51 comes into contact with the securing block 41. The screw 51 includes an enlarged knob 53 which is to facilitate manual rotation of the shaft 51. The knob 53 is mounted within a recess 55 formed within the handle grip 14.

Inward depressing movement of the trigger 16 causes movement of the valve sleeve 22 into the housing 12 against the bias of spring 24. The spring 24 is located within recess 26 formed within the sleeve 22, with one end of the spring 24 in contact with the sleeve 22 and the other end of the spring 24 in contact with a portion of the housing 12. An extension 28 of the sleeve 22 extends through the center of the coil spring 24 and passes through opening 30 formed through the housing 12. Opening 30 communicates with chamber 32 also formed within the housing 12. A bolt 34 is threadably connected with respect to the housing 12 andextends within lateral aperture 36 formed within sleeve 22. Ap-

erture 36 is much larger than the diameter of bolt 34 and as a result the bolt 34 functions as a-stop to define the limits of movement of the sleeve 22 in respect to the housing 12.

Inward movement of the sleeve 22 causes the spring 24 to be compressed with the extension 28 causing a tilting movement of valve stem 38. When the valve stem 38 is tilted, the valve seat 40 is tilted against the bias of spring 42 away from the O-ring seal 44 fabricated from elastomeric or other suitable sealing material. The seal 44 is located against a radially inwardly extending shoulder located at the end of the inlet chamber 46 which is formed within the housing 12. A

nut 48 threadingly cooperates with the housing 12 and extends within inlet chamber 46. The nut 48 includes a central opening 50. The conduit 18 is threadably connected to the housing 22 so that the interior of conduit 18 communicates directly with the opening 50. Pressurized air passing through the conduit 18 is transmitted through conduit 50 and into the inlet chamber 46.

52 there is a chamber 54 in the space between the outer wall of conduit 52 and the inner wall of conduit 18.

Chamber 54 comprises an exhaust chamber through which the exhausted air is to be conducted and discharged in an area displaced from the tool 10. This is desirable so that there will not be any noise or aggravation due to a blast of air in the proximity of the tool during use.

Rotatably mounted within the housing 12 by means of a pin 56 is a plug 58. Radially extending outwardly adjacent and surrounding the opening 68 is an O-ring seal 70 which is to form an air-tight connection with the housing 12. Located about the O-ring seal 70 is an exhaust groove 72. Formed within the housing 12 and communicating with both the exhaust groove 72 and the exhaust chamber 54 are a plurality of exhaust openings 74. There are six such openings 74 being employed but it is to be understood that this is a matter of choice or design. The length of the groove 72 is to be sufficient so that no matter to what position the valve disc is moved, all six of the openings 74 will be in communication with the groove 72. In actual practice, the groove 72 extends approximately 300 about the disc 66.

Extending completely through the disc 66 and connecting with the exhaust groove 72 is a first exhaust opening 76 and a second exhaust opening 78. The function of these openings 76 and 78 will be explained further on in this specification.

Formed through the disc 66 is an elongated opening 80 which is also in communication with the exhaust groove 72. The cylinder 82 of a first motor unit has a pin 84 extending therefrom. The pin 84 is to extend through the opening 80 and into a hole 86 formed within the housing 12. Cooperation between the pin 84 and the hole 86 functions to fix the cylinder 82 in respect to the housing 12.

Formed within the cylinder 82 is a first kidney opening 88 and a second kidney opening 90. Openings 88 and 90 are approximately in the same area as openings 76 and 78 formed within the disc 66. With the plug 58 rotated as far as possible clockwise, the pin 60 is moved to effect pivoting of the valve disc 66 .so that the second exhaust opening 78 is in direct communication with the first kidney-shaped opening 88. ln this position the second kidney-shaped opening 90 is in communication with a keyway type of groove 92 formed in the front side of the disc 66. As a result, inlet air is being conducted from the center opening 68 into the keyway type groove 92 and into opening 90 with air being ex.- hausted through opening 88 into opening 78 through opening 74 and into chamber 54.

When the plug 58 is moved counterclockwise, the second kidney-shaped opening 90 communicates directly with the first exhaust opening 76. Since the exhaust opening 76 communicates directly with the exhaust groove 72, the same as does opening 74, the air is exhausted in the same manner as previously described. The first kidney-shaped opening 88 now communicates with the keyway groove 92 so that the air is now received into opening 88 and discharged through opening 90. The foregoing procedure is to effect a reversal of the driving motion of the motor assembly (which nowwill be described in detail).

Extending through the cylinder 82 is a bleed opening The groove 96 communicates with a biasing chamber 98 formed also within the housing 12. Opening 94 is in communication with a kidney-shaped groove 100 formed within the disc 66. The groove 100 is directly connected to the inlet chamber 32. Therefore, inlet air is caused to be continuously communicated through the groove 100 through opening 94 and into the chamber 98. The function of the chamber 98 will be explained further on in the specification.

Located within the cylinder 82 is a motor chamber 102. The rotor 104 is fixedly connected to a shaft 106 with the rotor 104 being rotatably supported within the 94. Bleed opening 94 extends to the periphery of the cylinder 82 and communicates with an annular groove 96 formed within an interior wall of the housing 12.

' chamber 102 by means of a bearing 108 which supports the end of the shaft 106 in respect to the cylinder 82. The rotor 104 is eccentrically mounted upon the shaft 106. The free end of the rotor 104 abuts a separation plate 110. Plate 110 is rotatably mounted with respect to the shaft 106 by means of bearings 1 12 and 114. The rotor 104 has a portion removed therefrom to form a recess 116. Recess 116 is formed so that the rotor 104 will be dynamically balanced in respect to the shaft 106. A thin metal sleeve 118 surrounds the rotor 104 in a tight fitting manner so as to enclose the recess 1 16.

The separation plate 110 functions to separate the first motor unit from-a second motor unit. Passing through the separation plate 110 are openings 120 and 122 which are to cooperate respectively with openings 90 and 88. The separation plate 110 also includes an alignment pin 124. The pin 124 is to matingly cooperate within an opening (not shown) within the cylinder 82 and also to cooperate within an opening 126 formed within cylinder 128 of the second motor unit. As a result, the separation plate 110 is fixed in relation to its cylinders 128 and 82 which are in turn fixed in relation to the housing 12.

Formed within the cylinder 82 is an elongated opening 130. A shroud 132 is to be slidably mounted within the opening 130 and is adapted to be in continuous contact with the sleeve 118 of the rotor 104 and also to communicate continuously with opening 98. The air pressure within the chamber 98 exerts-a continuous bias upon the shroud 132 tending to maintain such in contact with sleeve 104. It is to be noted that the shroud 132 is mounted directly between the ports 88 and 90 and extends the entire length of the chamber 110.

A second motor unit is essentially the same as the first motor unit and includes a rotor 134 which is eccentrically mounted on the shaft 106. The rotor 134 is relieved to form a recess 136 at its enlarged end so as to dynamically balance such. A sleeve 138 surrounds the rotor 134 in order to cover the recess 136. The rotor 134 is rotatably mounted within a chamber 140 formed within the cylinder 128. The cylinder 128 also includes kidney-shaped ports 142 and 144 which are to communicate respectively with openings 122 and 120. Extending through the cylinder 128 is an opening 146 which is to movably support a shroud 148. Shroud 148 communicates with the air chamber 98 and is continuously biased in the contact with the sleeve 138 of the rotor 134. The shrouds 148 and 132 are normally constructed of fiberglass or a type of plastic material. The shrouds 132 and 148 must be constructed of a substantially rigid material.

The shaft 106 is rotatably supported by means of a bearing 150 in respect to the cylinder 128. It is to be noted that the rotors 104 and 134 are mounted so that their enlarged ends extend opposite each other (in other words, 180 out-of-phase). This tandem mounting arrangement is such that if perchance a single motor unit is stopped exactly dead center, by supplying inlet air the secondmotor unit will provide the initial rotational torque until the first motor unit is capable of operating.

It is further to be noted that in referring particularly to FIGS. 8 and 9 of the drawings, one side of each of the rotors 104 and 134 are rounded to conform to the configuration of the wall of the chambers 110 and 140. This is so that the rotors 104 and 134 will make an area type of contact with their respective cylinder so as to preclude leakage of air past the rotor from the inlet side to the exhaust side. If this was not accomplished, there would be substantial leakage therebetween because of only a line contact being established by the rotor with the cylinder wall Referring in particular to FIG. 3 of the drawings, the shaft 106 is connected to the attachment with the attachment 20 being rotatably supported by means of bearings 152 and 154 in respect to an attachment housing 156. Attachment housing 156 is threadably mounted to the housing 12. If desired, the different attachment housing 156 can be threadably mounted to the housing 12 with attachments such as a saw, a drill, or the like being employed instead of the router depicted in FIGS. 1 and 2 of the drawings.

The operation of this invention is as follows: The operator by depressing trigger 16 causes inward movement of the sleeve 22 to thereby tilt the valve stem 38 and cause air to be supplied from interiorly of conduit 52 into chamber 32. The air is then conducted into center opening 68 into valve disc 66 and into either opening 76 or 78 of the valve disc 66. This selection is accomplished by which way the plug 58 has been rotated to its maximum position (either clockwise or counterclockwise) as was previously described. The air is then caused to be conducted into either port 88 or 90 and from there into chamber 110 on one side of the rotor 104. The same holds true for rotor 134 mounted within chamber 140. As a result, the rotors 104 and 134 are rotatably driven in the same direction (depending on which side of the rotor air is being supplied to). Whatever port 88 or 90 is supplying airinto chamber 110, the opposite port is extracting air from the chamber 110. The same is true for ports 142 and 144. The exhausted air is conducted into the exhaust groove 72 and into the exhaust chamber 54 as previously described.

What is claimed is:

1. In combination with an air operated tool wherein said tool includes a motor unit, said motor unit to drive a tool attachment, said motor unit being mounted within a housing, said housing having a series of convolutions formed thereon, a handle grip assembly adapted to connect with said housing, said handle grip assembly comprising:

a handle grip housing, a securing block pivotally mounted by pivot means to said handle grip housing, securing means mounted within said handle grip housing adapted to contact said securing block, said-securing means being movable to cause pivoting movement of said securing block into tight engagement with one of said convolutions, thereby securing together said handle grip housing and said motor housing.

2. The tool as defined in claim 1 wherein:

said motor housing having an inlet for pressurized air,

' said inlet including a valve, said valve being normally closed so as to not permit entry of pressurized air, said valve including a valve sleeve extending exteriorly of said motor housing in the area of said convolutions, a trigger being pivotally mounted by pivot means upon said handle grip housing, said trigger to contact said valve sleeve, whereby upon manual depressing movement of said trigger said valve sleeve is depressed thereby opening said valve and permitting entry of pressurized air to said motor unit.

3. The tool as defined in claim 2 wherein:

said pivot means comprises a single pivot pin whereby said trigger and said securing block are both mounted upon said pivot pin.

4. The tool as defined in claim 3 wherein:

said securing means comprises a set screw, said set screw being mounted for movement substantially parallel to the longitudinal axis of said housing.

5. The tool as defined in claim 3 wherein:

said securing means comprises an elongated screw mounted within said handle grip housing, said elongated screw being located substantially perpendicular to the longitudinal axis of said housing.

6. The tool as defined in claim 3 wherein:

the foremost convolution being enlarged whereby said a'ftmost convolution functions as a stop to the insertion movement of said handle grip housing and said motor housing. 

1. In combination with an air operated tool wherein said tool includes a motor unit, said motor unit to drive a tool attachment, said motor unit bEing mounted within a housing, said housing having a series of convolutions formed thereon, a handle grip assembly adapted to connect with said housing, said handle grip assembly comprising: a handle grip housing, a securing block pivotally mounted by pivot means to said handle grip housing, securing means mounted within said handle grip housing adapted to contact said securing block, said securing means being movable to cause pivoting movement of said securing block into tight engagement with one of said convolutions, thereby securing together said handle grip housing and said motor housing.
 2. The tool as defined in claim 1 wherein: said motor housing having an inlet for pressurized air, said inlet including a valve, said valve being normally closed so as to not permit entry of pressurized air, said valve including a valve sleeve extending exteriorly of said motor housing in the area of said convolutions, a trigger being pivotally mounted by pivot means upon said handle grip housing, said trigger to contact said valve sleeve, whereby upon manual depressing movement of said trigger said valve sleeve is depressed thereby opening said valve and permitting entry of pressurized air to said motor unit.
 3. The tool as defined in claim 2 wherein: said pivot means comprises a single pivot pin whereby said trigger and said securing block are both mounted upon said pivot pin.
 4. The tool as defined in claim 3 wherein: said securing means comprises a set screw, said set screw being mounted for movement substantially parallel to the longitudinal axis of said housing.
 5. The tool as defined in claim 3 wherein: said securing means comprises an elongated screw mounted within said handle grip housing, said elongated screw being located substantially perpendicular to the longitudinal axis of said housing.
 6. The tool as defined in claim 3 wherein: the foremost convolution being enlarged whereby said aftmost convolution functions as a stop to the insertion movement of said handle grip housing and said motor housing. 